File Redirection and Roaming Profiles

I am running Win 2K Server, SP4, with Win XP Clients. The users have roaming profiles. I want to redirect the My Docs folder so that the documents do not transit accross the LAN with the profile. I have tried using GPO, by doing a basic redirection of the My Docs folder to \\servername\users$\%username%. This is on the GPO for a single OU, with all the users in it. However, when I log in, it does not appear to work. When I look on the server, all the docs are still in the profile, and none in the users directory? What am I doing wrong? Do I need to make this policy part of the default Domain GPO? I though OU superceded domain in the hierarchy?